Pub Date : 2026-02-06DOI: 10.1016/j.ast.2026.111866
Samandar Khan Afridi , Shakoor Akhtar , Talha Zafar Khan , Mohsin Ali Koondhar , Ibrahim Mahariq , Ezzeddine Touti
This paper investigates the feasibility and effectiveness of a Parachute Recovery System (PRS) as an advanced airframe safety enhancement for commercial aircraft, focusing on the Boeing 777. A mixed-methods approach integrates analytical, order-of-magnitude aerodynamic modeling, expert qualitative assessments, and real-world case studies. Simulation results indicate a generated drag force of approximately 26.4 kN, demonstrating the PRS capability to achieve limited drag contribution under idealized descent assumptions during in-flight emergencies. Evidence from Cirrus SR20 and SR22 aircraft further validates PRS performance, achieving safe, low-impact landings with high survivability rates. However, large-scale implementation poses considerable engineering, financial, and regulatory challenges, including structural reinforcement, deployment reliability, and certification complexity. The cost-benefit analysis suggests that although initial and maintenance costs are significant, they may be offset by long-term safety improvements and reduced insurance liabilities. The study recommends the integration of lightweight composite materials, multi-stage deployment systems, comprehensive testing, and specialized pilot training, alongside collaboration among manufacturers, airlines, and regulatory authorities to streamline certification and operational adoption. The findings highlight the potential of PRS to advance next-generation aviation safety, enhance passenger survivability, and establish new benchmarks in commercial aircraft design and emergency recovery systems.
{"title":"Exploring the feasibility of parachute recovery systems for catastrophic failures in passenger aircraft","authors":"Samandar Khan Afridi , Shakoor Akhtar , Talha Zafar Khan , Mohsin Ali Koondhar , Ibrahim Mahariq , Ezzeddine Touti","doi":"10.1016/j.ast.2026.111866","DOIUrl":"10.1016/j.ast.2026.111866","url":null,"abstract":"<div><div>This paper investigates the feasibility and effectiveness of a Parachute Recovery System (PRS) as an advanced airframe safety enhancement for commercial aircraft, focusing on the Boeing 777. A mixed-methods approach integrates analytical, order-of-magnitude aerodynamic modeling, expert qualitative assessments, and real-world case studies. Simulation results indicate a generated drag force of approximately 26.4 kN, demonstrating the PRS capability to achieve limited drag contribution under idealized descent assumptions during in-flight emergencies. Evidence from Cirrus SR20 and SR22 aircraft further validates PRS performance, achieving safe, low-impact landings with high survivability rates. However, large-scale implementation poses considerable engineering, financial, and regulatory challenges, including structural reinforcement, deployment reliability, and certification complexity. The cost-benefit analysis suggests that although initial and maintenance costs are significant, they may be offset by long-term safety improvements and reduced insurance liabilities. The study recommends the integration of lightweight composite materials, multi-stage deployment systems, comprehensive testing, and specialized pilot training, alongside collaboration among manufacturers, airlines, and regulatory authorities to streamline certification and operational adoption. The findings highlight the potential of PRS to advance next-generation aviation safety, enhance passenger survivability, and establish new benchmarks in commercial aircraft design and emergency recovery systems.</div></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":"173 ","pages":"Article 111866"},"PeriodicalIF":5.8,"publicationDate":"2026-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146134792","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-06DOI: 10.1016/j.ast.2026.111852
Jiliang Xie, Kemao Ma
A nonzero-sum Target-Attacker-Defender game is investigated, where the target attempts to evade the attacker, the attacker aims to capture the target while evading the defenders, and the multiple defenders strive to capture the attacker while achieving the cooperation among them. A new class of cost functions segmented by the game times are developed to reflect the objectives of the respective agents. By optimizing these cost functions, the optimal strategies of the agents are derived, forming an equilibrium solution of the differential game. Furthermore, considering the communication interactions between the defenders, distributed defending strategies are derived for the defenders, where each defender’s strategy depends only on its own information and that of its connected neighbors. It is proved that the distributed strategies of the defenders, together with the optimal strategies of the target and the attacker, form an ϵ equilibrium solution of the differential game. The designed strategies are applied to a terminal guidance scenario, where a tactical missile intercepts an actively-defended target. Simulations are conducted to verify the effectiveness of the design.
{"title":"Distributed defending strategies in target-attacker-defender game with applications to cooperative guidance","authors":"Jiliang Xie, Kemao Ma","doi":"10.1016/j.ast.2026.111852","DOIUrl":"10.1016/j.ast.2026.111852","url":null,"abstract":"<div><div>A nonzero-sum Target-Attacker-Defender game is investigated, where the target attempts to evade the attacker, the attacker aims to capture the target while evading the defenders, and the multiple defenders strive to capture the attacker while achieving the cooperation among them. A new class of cost functions segmented by the game times are developed to reflect the objectives of the respective agents. By optimizing these cost functions, the optimal strategies of the agents are derived, forming an equilibrium solution of the differential game. Furthermore, considering the communication interactions between the defenders, distributed defending strategies are derived for the defenders, where each defender’s strategy depends only on its own information and that of its connected neighbors. It is proved that the distributed strategies of the defenders, together with the optimal strategies of the target and the attacker, form an ϵ equilibrium solution of the differential game. The designed strategies are applied to a terminal guidance scenario, where a tactical missile intercepts an actively-defended target. Simulations are conducted to verify the effectiveness of the design.</div></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":"173 ","pages":"Article 111852"},"PeriodicalIF":5.8,"publicationDate":"2026-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146134793","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-06DOI: 10.1016/j.ast.2026.111773
Kapil Aryal , Vivek Nair , Nishith K R Gorla , Sandeep Patil , Brian H. Dennis
This paper compares two non-intrusive reduced-order models for predicting surface-pressure fields in inverse airfoil shape identification with deforming meshes. Proper Orthogonal Decomposition (POD) and feed-forward neural networks map geometric and flow parameters to POD coefficients for rapid field reconstruction. The models are trained on 200 CFD snapshots of steady two-dimensional laminar separated flow () using either coarse or fine meshes to quantify accuracy-cost trade-offs. Results show that the coarse-mesh model achieves accuracy similar to the fine-mesh model while reducing offline training cost by nearly sixfold. Both models exhibit similar robustness in inverse design under noisy targets, and the reduced-order formulation smooths discretization-induced noise in the objective function, improving optimizer convergence.
{"title":"Inverse airfoil shape identification using POD-ANN ROMs: A coarse Mesh approach for computational efficiency","authors":"Kapil Aryal , Vivek Nair , Nishith K R Gorla , Sandeep Patil , Brian H. Dennis","doi":"10.1016/j.ast.2026.111773","DOIUrl":"10.1016/j.ast.2026.111773","url":null,"abstract":"<div><div>This paper compares two non-intrusive reduced-order models for predicting surface-pressure fields in inverse airfoil shape identification with deforming meshes. Proper Orthogonal Decomposition (POD) and feed-forward neural networks map geometric and flow parameters to POD coefficients for rapid field reconstruction. The models are trained on 200 CFD snapshots of steady two-dimensional laminar separated flow (<span><math><mrow><mi>R</mi><mi>e</mi><mo>=</mo><mn>1000</mn></mrow></math></span>) using either coarse or fine meshes to quantify accuracy-cost trade-offs. Results show that the coarse-mesh model achieves accuracy similar to the fine-mesh model while reducing offline training cost by nearly sixfold. Both models exhibit similar robustness in inverse design under noisy targets, and the reduced-order formulation smooths discretization-induced noise in the objective function, improving optimizer convergence.</div></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":"174 ","pages":"Article 111773"},"PeriodicalIF":5.8,"publicationDate":"2026-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146134790","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-05DOI: 10.1016/j.ast.2026.111857
Xintao Zhang , Gang Sun , Lijuan Feng , Yongfeng Jin , Anran Ju
With the increasing diameter of high-bypass-ratio turbofan nacelles, reducing nacelle weight has become a critical design objective. Shortening the inlet length is an effective approach to achieve this goal but poses challenges under crosswind conditions due to flow separation and distortion risks. This study investigates the aerodynamic characteristics and optimization of short inlets subjected to crosswind. A distortion mechanism is revealed, showing that the coupling between the unsteady ground vortex and the diffuser flow is the key cause of flow instability and pressure distortion. Based on steady-state computational fluid dynamics analysis, a wall-velocity-based criterion is proposed for rapid engineering assessment of separation. A decoupled intuitive class shape transformation (DiCST) parameterization method is developed to independently control the fore-body and aft-body of the inlet, enhancing local shaping flexibility. Furthermore, a multi-objective optimization framework combining support vector machines with a genetic algorithm is established, transforming distortion evaluation into a flow-separation classification problem. The optimized short inlet achieves a length reduction of approximately 0.05 times the engine diameter in average while maintaining distortion within acceptable limits. Wind tunnel tests confirm that the optimized configuration suppresses flow separation effectively under crosswind conditions, validating the proposed design methodology.
{"title":"Aerodynamic optimization strategy and experimental study on short inlet in crosswind conditions using decoupled intuitive class shape transformation curves","authors":"Xintao Zhang , Gang Sun , Lijuan Feng , Yongfeng Jin , Anran Ju","doi":"10.1016/j.ast.2026.111857","DOIUrl":"10.1016/j.ast.2026.111857","url":null,"abstract":"<div><div>With the increasing diameter of high-bypass-ratio turbofan nacelles, reducing nacelle weight has become a critical design objective. Shortening the inlet length is an effective approach to achieve this goal but poses challenges under crosswind conditions due to flow separation and distortion risks. This study investigates the aerodynamic characteristics and optimization of short inlets subjected to crosswind. A distortion mechanism is revealed, showing that the coupling between the unsteady ground vortex and the diffuser flow is the key cause of flow instability and pressure distortion. Based on steady-state computational fluid dynamics analysis, a wall-velocity-based criterion is proposed for rapid engineering assessment of separation. A decoupled intuitive class shape transformation (DiCST) parameterization method is developed to independently control the fore-body and aft-body of the inlet, enhancing local shaping flexibility. Furthermore, a multi-objective optimization framework combining support vector machines with a genetic algorithm is established, transforming distortion evaluation into a flow-separation classification problem. The optimized short inlet achieves a length reduction of approximately 0.05 times the engine diameter in average while maintaining distortion within acceptable limits. Wind tunnel tests confirm that the optimized configuration suppresses flow separation effectively under crosswind conditions, validating the proposed design methodology.</div></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":"174 ","pages":"Article 111857"},"PeriodicalIF":5.8,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146134794","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-05DOI: 10.1016/j.ast.2026.111844
Nihat Çabuk
This study presents a real-time geometry-aware control strategy and its experimental validation for quadrotor UAVs equipped with actively adjustable dihedral angles. By integrating a cascaded PID control architecture with dynamic dihedral modulation, the system adapts its aerodynamic configuration during flight to enhance stability and responsiveness. Unlike conventional fixed-geometry multirotors, this platform enables geometric tuning in flight via a centralized actuation mechanism. Nonlinear simulations and autonomous flight tests were conducted for five different dihedral configurations () under identical flight scenarios, including takeoff, hover and landing. Performance metrics such as altitude accuracy, attitude stability (roll, pitch, yaw), and structural vibration levels were analyzed. The findings validate the feasibility and effectiveness of geometry-aware control for multirotor systems. In addition, this work introduces a novel class of UAVs capable of real-time structural reconfiguration, enabling adaptation to changing flight conditions, payload variations, or mission profiles.
{"title":"Design and implementation of real-time dihedral angle control for enhanced flight stability of quadrotor UAV","authors":"Nihat Çabuk","doi":"10.1016/j.ast.2026.111844","DOIUrl":"10.1016/j.ast.2026.111844","url":null,"abstract":"<div><div>This study presents a real-time geometry-aware control strategy and its experimental validation for quadrotor UAVs equipped with actively adjustable dihedral angles. By integrating a cascaded PID control architecture with dynamic dihedral modulation, the system adapts its aerodynamic configuration during flight to enhance stability and responsiveness. Unlike conventional fixed-geometry multirotors, this platform enables geometric tuning in flight via a centralized actuation mechanism. Nonlinear simulations and autonomous flight tests were conducted for five different dihedral configurations (<span><math><mrow><mi>γ</mi><mo>=</mo><mo>−</mo><msup><mn>7</mn><mo>∘</mo></msup><mo>,</mo><mo>−</mo><mn>3</mn><mo>.</mo><msup><mn>5</mn><mo>∘</mo></msup><mo>,</mo><msup><mn>0</mn><mo>∘</mo></msup><mo>,</mo><mo>+</mo><mn>3</mn><mo>.</mo><msup><mn>5</mn><mo>∘</mo></msup><mo>,</mo><mo>+</mo><msup><mn>7</mn><mo>∘</mo></msup></mrow></math></span>) under identical flight scenarios, including takeoff, hover and landing. Performance metrics such as altitude accuracy, attitude stability (roll, pitch, yaw), and structural vibration levels were analyzed. The findings validate the feasibility and effectiveness of geometry-aware control for multirotor systems. In addition, this work introduces a novel class of UAVs capable of real-time structural reconfiguration, enabling adaptation to changing flight conditions, payload variations, or mission profiles.</div></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":"173 ","pages":"Article 111844"},"PeriodicalIF":5.8,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146134808","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-05DOI: 10.1016/j.ast.2026.111843
Dechuan Ma, Gaohua Li, Jiahao Liu, Can Liu, Fuxin Wang
Dynamic stall on helicopter retreating blades involves complex flow phenomena, particularly with the emergence of local supersonic regions and shock waves. This study investigates the force generation mechanisms of a pitching NACA0012 wing section in dynamic stall using improved delayed detached eddy simulations (IDDES). At a moderate Reynolds number of and reduced frequencies and 0.25, the compressibility effects are examined by varying the freestream Mach number (, 0.3, and 0.5). An extended force partitioning method (E-FPM) is proposed to establish a direct linkage between flow fields and aerodynamic forces in compressible flows. In all cases, the majority of force production is attributed to the second Galilean invariant of the velocity gradient tensor, while the remainder arises from nonzero velocity divergence and density fluctuations due to compressibility. Prior to stall onset, leading-edge suction dominates lift and drag production, and turbulent separation vortices (TSVs) also have a positive contribution. As M∞ increases, the leading-edge stagnation point moves upstream. The insufficient flow acceleration reduces fluid stretching and strain around the high-curvature leading edge, causing a loss in lift when M∞ reaches 0.5. Upon stall onset, the dynamic stall vortex (DSV) becomes the main force contributor. At higher M∞, the DSV forms earlier due to advanced stall onset, which leads to earlier drag divergence and increased drag. However, the DSV also sheds earlier and weakens with enhanced compressibility. The reduced vorticity and increased density fluctuations within the vortex core region of the DSV result in lower peak lift and drag. With the DSV shedding, its positive contribution from the vortex core region diminishes without vorticity feed. The negative contribution from the vortex-induced stretching and strain becomes dominant and leads to lift stall. This work provides new insights into compressible dynamic stall physics and demonstrates the E-FPM’s effectiveness in identifying the physical origins of aerodynamic forces in such compressible, vortex-dominated flows.
{"title":"Correlation between aerodynamic forces and vortex dynamics of a NACA0012 wing section in compressible dynamic stall via IDDES","authors":"Dechuan Ma, Gaohua Li, Jiahao Liu, Can Liu, Fuxin Wang","doi":"10.1016/j.ast.2026.111843","DOIUrl":"10.1016/j.ast.2026.111843","url":null,"abstract":"<div><div>Dynamic stall on helicopter retreating blades involves complex flow phenomena, particularly with the emergence of local supersonic regions and shock waves. This study investigates the force generation mechanisms of a pitching NACA0012 wing section in dynamic stall using improved delayed detached eddy simulations (IDDES). At a moderate Reynolds number of <span><math><mrow><mi>R</mi><msub><mi>e</mi><mi>c</mi></msub><mo>=</mo><mn>500</mn><mo>,</mo><mn>000</mn></mrow></math></span> and reduced frequencies <span><math><mrow><mi>k</mi><mo>=</mo><mn>0.15</mn></mrow></math></span> and 0.25, the compressibility effects are examined by varying the freestream Mach number (<span><math><mrow><msub><mi>M</mi><mi>∞</mi></msub><mo>=</mo><mn>0.1</mn></mrow></math></span>, 0.3, and 0.5). An extended force partitioning method (E-FPM) is proposed to establish a direct linkage between flow fields and aerodynamic forces in compressible flows. In all cases, the majority of force production is attributed to the second Galilean invariant of the velocity gradient tensor, while the remainder arises from nonzero velocity divergence and density fluctuations due to compressibility. Prior to stall onset, leading-edge suction dominates lift and drag production, and turbulent separation vortices (TSVs) also have a positive contribution. As <em>M</em><sub>∞</sub> increases, the leading-edge stagnation point moves upstream. The insufficient flow acceleration reduces fluid stretching and strain around the high-curvature leading edge, causing a loss in lift when <em>M</em><sub>∞</sub> reaches 0.5. Upon stall onset, the dynamic stall vortex (DSV) becomes the main force contributor. At higher <em>M</em><sub>∞</sub>, the DSV forms earlier due to advanced stall onset, which leads to earlier drag divergence and increased drag. However, the DSV also sheds earlier and weakens with enhanced compressibility. The reduced vorticity and increased density fluctuations within the vortex core region of the DSV result in lower peak lift and drag. With the DSV shedding, its positive contribution from the vortex core region diminishes without vorticity feed. The negative contribution from the vortex-induced stretching and strain becomes dominant and leads to lift stall. This work provides new insights into compressible dynamic stall physics and demonstrates the E-FPM’s effectiveness in identifying the physical origins of aerodynamic forces in such compressible, vortex-dominated flows.</div></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":"173 ","pages":"Article 111843"},"PeriodicalIF":5.8,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146134810","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-05DOI: 10.1016/j.ast.2026.111863
Jintao Hu , Min Chen , Jiyuan Zhang , Yihao Xu , Hailong Tang
Accurate state estimation is critical for performance optimization and reliability enhancement in modern turbine systems. Although traditional filtering methods have demonstrated strong performance in various applications, their effectiveness is limited in the presence of component performance dispersion, high-dimensional system dynamics, performance degradation and uncertain control inputs. This study proposes a variational inference-based state estimation framework for aero-engine systems to address challenges arising from multi-source uncertainty. Under the assumption of a known state-space model, a loss function based on the stochastic variational lower bound is constructed to enable joint optimization of state variables and model parameters. This allows for precise inference of component health states and reliable identification of fault-related features. In cases where the aero-engine system model is partially or completely unknown, a hierarchical variational framework is further introduced, incorporating stochastic differential equations to simultaneously infer system states and uncover underlying control dynamics. Simulation results demonstrate that the proposed method consistently outperforms traditional filtering algorithms under varying noise levels and model uncertainties. It effectively distinguishes between modeling errors and actual performance deviations of engine components, leading to improved diagnostic accuracy and robustness.
{"title":"State estimation and system model correction of aero-engines under multi-source uncertainty: A hierarchical variational inference approach","authors":"Jintao Hu , Min Chen , Jiyuan Zhang , Yihao Xu , Hailong Tang","doi":"10.1016/j.ast.2026.111863","DOIUrl":"10.1016/j.ast.2026.111863","url":null,"abstract":"<div><div>Accurate state estimation is critical for performance optimization and reliability enhancement in modern turbine systems. Although traditional filtering methods have demonstrated strong performance in various applications, their effectiveness is limited in the presence of component performance dispersion, high-dimensional system dynamics, performance degradation and uncertain control inputs. This study proposes a variational inference-based state estimation framework for aero-engine systems to address challenges arising from multi-source uncertainty. Under the assumption of a known state-space model, a loss function based on the stochastic variational lower bound is constructed to enable joint optimization of state variables and model parameters. This allows for precise inference of component health states and reliable identification of fault-related features. In cases where the aero-engine system model is partially or completely unknown, a hierarchical variational framework is further introduced, incorporating stochastic differential equations to simultaneously infer system states and uncover underlying control dynamics. Simulation results demonstrate that the proposed method consistently outperforms traditional filtering algorithms under varying noise levels and model uncertainties. It effectively distinguishes between modeling errors and actual performance deviations of engine components, leading to improved diagnostic accuracy and robustness.</div></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":"174 ","pages":"Article 111863"},"PeriodicalIF":5.8,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146135571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-05DOI: 10.1016/j.ast.2026.111860
Ayushmaan Singh
This study experimentally investigates fluidic thrust vectoring (FTV) in a Mach 1.6 axisymmetric jet using pulsed transverse air injection located 3.57 mm upstream of the nozzle exit. The influence of actuation frequency, duty cycle, and momentum ratio on jet deflection and vectoring efficiency is systematically examined, with direct comparison between steady and pulsed injection modes. Experiments were conducted using a precision-machined converging–diverging nozzle, employing wall-pressure measurements, total-pressure rake diagnostics, and Schlieren visualisation. Results show that pulsed injection consistently achieves higher mass-specific vectoring efficiency than steady injection at identical supply pressures, producing comparable jet deflection with reduced secondary mass flow. Maximum efficiency is observed at low duty cycles (20–25%) and forcing frequencies near 200 Hz. Numerical characterisation using a convective timescale and corresponding Strouhal number indicates that this frequency range aligns with dominant supersonic shear-layer instability modes. Analytical scaling relations and symbolic manipulation reveal a nonlinear dependence of vectoring efficiency on duty cycle and frequency, explaining the observed transition between efficient unsteady forcing and quasi-steady behaviour. Schlieren images confirm periodic bow-shock oscillations and transient asymmetry under pulsed actuation, demonstrating the effectiveness of unsteady fluidic control for supersonic jet vectoring.
{"title":"Experimental investigation of pulsed fluidic thrust vectoring in a Mach 1.6 axisymmetric jet using transverse air injection for enhanced vectoring efficiency","authors":"Ayushmaan Singh","doi":"10.1016/j.ast.2026.111860","DOIUrl":"10.1016/j.ast.2026.111860","url":null,"abstract":"<div><div>This study experimentally investigates fluidic thrust vectoring (FTV) in a Mach 1.6 axisymmetric jet using pulsed transverse air injection located 3.57 mm upstream of the nozzle exit. The influence of actuation frequency, duty cycle, and momentum ratio on jet deflection and vectoring efficiency is systematically examined, with direct comparison between steady and pulsed injection modes. Experiments were conducted using a precision-machined converging–diverging nozzle, employing wall-pressure measurements, total-pressure rake diagnostics, and Schlieren visualisation. Results show that pulsed injection consistently achieves higher mass-specific vectoring efficiency than steady injection at identical supply pressures, producing comparable jet deflection with reduced secondary mass flow. Maximum efficiency is observed at low duty cycles (20–25%) and forcing frequencies near 200 Hz. Numerical characterisation using a convective timescale and corresponding Strouhal number indicates that this frequency range aligns with dominant supersonic shear-layer instability modes. Analytical scaling relations and symbolic manipulation reveal a nonlinear dependence of vectoring efficiency on duty cycle and frequency, explaining the observed transition between efficient unsteady forcing and quasi-steady behaviour. Schlieren images confirm periodic bow-shock oscillations and transient asymmetry under pulsed actuation, demonstrating the effectiveness of unsteady fluidic control for supersonic jet vectoring.</div></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":"173 ","pages":"Article 111860"},"PeriodicalIF":5.8,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146134789","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-05DOI: 10.1016/j.ast.2026.111861
Xiaohu Chen , Ziheng Hong , Mingtao Zang , Ziyu Jia , Lianfeng Yang , Yanhua Wang , Zhongyi Wang , Yuzhang Wang
To address the challenge of predicting particle deposition characteristics on high-temperature air-cooled turbine in aero-engines, this work develops a high-temperature particle collision and deposition criterion based on the Weber number of molten particles. The effects of film cooling blowing ratio, hole geometry, particle diameter, and thermal barrier coatings (TBCs) on particle deposition behavior near film cooling holes are analyzed. The proposed model accurately predicts particle transport and deposition under large thermal gradients within air-cooled turbine cascade passages across a wide temperature range. Results show that particles are mainly deposited at the exits of the film cooling holes, in the leading-edge stagnation regions, and between the downstream cooling zones, forming pronounced internal blockage, horseshoe-shaped accumulation region, and ridge-like deposition band, respectively. With increasing blowing ratio, both deposition efficiency and deposition rate decrease nonlinearly, and the downstream ridge-like deposition becomes more prominent. When the blowing ratio increases from M = 0.5 to M = 3, particle deposition efficiency decreases by approximately 67 %. Compared with cylindrical holes, fan-shaped holes reduce total particle deposition by 5 %-42 % and suppress the downstream ridge deposition pattern, but increase deposition inside the holes. Applying TBCs increases the overall particle deposition rate by 14 %-27 %, enhances surface deposition, and accentuates the downstream ridge-like deposition structures. The particle diffusion deposition mechanism (St < 0.1), particle diffusion-collision deposition mechanism (0.1 < St < 1), and particle inertial buffering deposition mechanism (St > 1) are the main causes of the aforementioned deposition characteristics. Different blowing ratios, hole geometries, and TBCs all change the spatial scale and intensity of the counter-rotating vortex pairs, which dominate the two basic transport physics of particle ejection and entrainment, thereby determining the particle deposition characteristics. This study provides theoretical insights and quantitative data to support an understanding of particle deposition, film hole blockage, cooling performance degradation, TBCs failure, and blade erosion in turbine environments.
{"title":"Mechanisms of particle deposition around film cooling holes on nozzle guide vanes in aero-engines","authors":"Xiaohu Chen , Ziheng Hong , Mingtao Zang , Ziyu Jia , Lianfeng Yang , Yanhua Wang , Zhongyi Wang , Yuzhang Wang","doi":"10.1016/j.ast.2026.111861","DOIUrl":"10.1016/j.ast.2026.111861","url":null,"abstract":"<div><div>To address the challenge of predicting particle deposition characteristics on high-temperature air-cooled turbine in aero-engines, this work develops a high-temperature particle collision and deposition criterion based on the Weber number of molten particles. The effects of film cooling blowing ratio, hole geometry, particle diameter, and thermal barrier coatings (TBCs) on particle deposition behavior near film cooling holes are analyzed. The proposed model accurately predicts particle transport and deposition under large thermal gradients within air-cooled turbine cascade passages across a wide temperature range. Results show that particles are mainly deposited at the exits of the film cooling holes, in the leading-edge stagnation regions, and between the downstream cooling zones, forming pronounced internal blockage, horseshoe-shaped accumulation region, and ridge-like deposition band, respectively. With increasing blowing ratio, both deposition efficiency and deposition rate decrease nonlinearly, and the downstream ridge-like deposition becomes more prominent. When the blowing ratio increases from M = 0.5 to M = 3, particle deposition efficiency decreases by approximately 67 %. Compared with cylindrical holes, fan-shaped holes reduce total particle deposition by 5 %-42 % and suppress the downstream ridge deposition pattern, but increase deposition inside the holes. Applying TBCs increases the overall particle deposition rate by 14 %-27 %, enhances surface deposition, and accentuates the downstream ridge-like deposition structures. The particle diffusion deposition mechanism (<em>St</em> < 0.1), particle diffusion-collision deposition mechanism (0.1 < <em>St</em> < 1), and particle inertial buffering deposition mechanism (<em>St</em> > 1) are the main causes of the aforementioned deposition characteristics. Different blowing ratios, hole geometries, and TBCs all change the spatial scale and intensity of the counter-rotating vortex pairs, which dominate the two basic transport physics of particle ejection and entrainment, thereby determining the particle deposition characteristics. This study provides theoretical insights and quantitative data to support an understanding of particle deposition, film hole blockage, cooling performance degradation, TBCs failure, and blade erosion in turbine environments.</div></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":"173 ","pages":"Article 111861"},"PeriodicalIF":5.8,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146135559","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-05DOI: 10.1016/j.ast.2026.111827
Yujie Gan , Huan Zhao , Zhengang Zhang , Keyao Gan
Natural laminar flow (NLF) design offers significant potential for reducing aerodynamic drag in green aviation to reduce fuel consumption, emissions, and noise. However, as the Mach number increases, it’s difficult for the current aerodynamic optimization method to balance maintaining an extended laminar flow region and weakening shockwaves for a lower drag coefficient, due to the multimodal characteristic of NLF design. Surrogate-based optimization is a promising solution meeting this requirement, but it encounters the serious curse of dimensionality, hindering its application for complex NLF design. To resolve this issue, a novel Partial Least Squares-based multi-level multi-fidelity sparse polynomial chaos-kriging (PLS-MLMF-PCK) surrogate model-assisted global optimization method for high-dimensional NLF design is proposed. PLS-MLMF-PCK enables more rapid and accurate prediction for high-dimensional problems by introducing PLS to modify the model’s kernel function of each level of fidelity in MLMF-PCK. This method selects the effective dimensionality for hyperparameters and builds the new kernel function in the covariance matrix to enhance the ability of creating the optimal MLMF-PCK. Further, a PLS-MLMF-PCK-assisted global optimization method with an adaptive multi-fidelity in-filling criterion is proposed. Results show that the new PLS-MLMF-PCK reduces computational costs by 60–95 % while improving prediction accuracy by 40–75 % in high-dimensional scenarios compared to the original MLMF-PCK. Further, it is validated that the advantages of this method scale with problem dimensionality, demonstrating robust performance for designs involving more than fifty variables. More importantly, the proposed method effectively alleviates dimensionality challenges and avoids getting stuck in a local optimum in high-dimensional global optimization for NLF or aerodynamic/multidisciplinary design.
{"title":"Novel partial least squares-based multi-level multi-fidelity polynomial chaos-Kriging for high-dimensional surrogate and optimization of natural laminar flow shape","authors":"Yujie Gan , Huan Zhao , Zhengang Zhang , Keyao Gan","doi":"10.1016/j.ast.2026.111827","DOIUrl":"10.1016/j.ast.2026.111827","url":null,"abstract":"<div><div>Natural laminar flow (NLF) design offers significant potential for reducing aerodynamic drag in green aviation to reduce fuel consumption, emissions, and noise. However, as the Mach number increases, it’s difficult for the current aerodynamic optimization method to balance maintaining an extended laminar flow region and weakening shockwaves for a lower drag coefficient, due to the multimodal characteristic of NLF design. Surrogate-based optimization is a promising solution meeting this requirement, but it encounters the serious curse of dimensionality, hindering its application for complex NLF design. To resolve this issue, a novel Partial Least Squares-based multi-level multi-fidelity sparse polynomial chaos-kriging (PLS-MLMF-PCK) surrogate model-assisted global optimization method for high-dimensional NLF design is proposed. PLS-MLMF-PCK enables more rapid and accurate prediction for high-dimensional problems by introducing PLS to modify the model’s kernel function of each level of fidelity in MLMF-PCK. This method selects the effective dimensionality for hyperparameters and builds the new kernel function in the covariance matrix to enhance the ability of creating the optimal MLMF-PCK. Further, a PLS-MLMF-PCK-assisted global optimization method with an adaptive multi-fidelity in-filling criterion is proposed. Results show that the new PLS-MLMF-PCK reduces computational costs by 60–95 % while improving prediction accuracy by 40–75 % in high-dimensional scenarios compared to the original MLMF-PCK. Further, it is validated that the advantages of this method scale with problem dimensionality, demonstrating robust performance for designs involving more than fifty variables. More importantly, the proposed method effectively alleviates dimensionality challenges and avoids getting stuck in a local optimum in high-dimensional global optimization for NLF or aerodynamic/multidisciplinary design.</div></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":"173 ","pages":"Article 111827"},"PeriodicalIF":5.8,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146134809","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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